Changing between units of measurement
There are two systems used for measuring quantities - metric and imperial.
The metric system uses three main units for measuring:
- length in metres (m)
- mass in kilograms (kg)
- volume in cubic metres (m3)
The imperial system uses the following units:
- length in inches, feet and yards
- mass in pounds (lb), ounces (oz) and stones
- volume in gallons
Converting metric units of length
The most common metric unit conversions for length are:
- 1 km = 1,000 m
- 1 m = 100 cm
- 1 cm = 10 mm
- 1 m = 1,000 mm
These can be used to convert the units used to measure length.
Example
The sunflower is 214 cm tall. Calculate the height of the sunflower in:
(a) metres
(b) millimetres
(a) 1 metre = 100 centimetres
So, \(214~\text{cm} = (214 \div 100)~\text{m} = 2.14~\text{m}\)
(b) 1 centimetre = 10 millimetres
So, \(214~\text{cm} = (214 \times 10)~\text{mm} = 2,140~\text{mm}\)
1 metre is longer than 1 centimetre, so to convert from metres to centimetres, multiply by 100. 1 millimetre is shorter than 1 centimetre so to convert from millimetres to centimetres, divide by 10.